Solve the system of equations
4x - 2y = 20
-8x + 4y = -40
Each one of the equations represents a line. The system of equations has a single solution if those lines are not parallel or coincident.
If we multiply the first equation by -2 we get:
-8x + 4y = -40
Note this is exactly the same expression as the second equation. This system of equations is really formed by a single equation because both lines coincide, they represent the very same line.
Such a system as infinitely many solutions.
For example, x=4, y=-2 is a solution
x = 0, y=-10 is another solution.
